Recently, plant-derived resins obtainable from plant resources have been noticed as an alternative for petroleum derived resins obtainable from petroleum resources as a raw material in viewpoint of decreasing environmental load. The plant-derived resins comprise raw materials obtainable from plants that are grown by photosynthesis while taking in CO2 in the air. Therefore, even if CO2 is exhausted by combustion treatment after use into the air, the amount of CO2 in the air is not increased in consequence. The plant-derived resins are so-called materials which correspond to carbon neutral and contribute a decrease of environmental load.
Soft polyurethane foams have been widely used as a cushioning material, and recently, they are used as a sound absorbing material used in the fields of cars and the like. However, as conventional polyurethane foams are formed from components derived from petroleum all, the development for the polyurethane foams taking into consideration the environment, for example depression of exhaustion of petroleum resources and decrease of CO2 exhausted, has been demanded.
As typical examples of polyol components used as a raw material for polyurethane foams, polyether polyol and polyester polyol derived from petroleum are known. Furthermore, it is known to use plant-derived castor oil, castor oil type polyols which are castor oil derivatives, or soybean oil type polyols which are soybean oil derivatives. For example, Patent document 1 discloses that aromatic diisocyanate is allowed to react with castor oil to form a prepolymer, and the prepolymer is allowed to react with water to form a polyurethane foam, and Patent document 2 discloses a process for producing a polyurethane foam by using a castor oil derivative such as hydrogenated castor oil or the like as an additive. Meanwhile, Patent document 3 discloses that an ester group-containing condensate (average molecular weight: 900 to 4500) prepared from recinoleic acid which is a main component of castor oil aliphatic acid, and mono- or more-hydric alcohol is used as an internal mold release agent in producing finely porous soft polyurethane molded articles, and Patent Document 4 discloses that a polyester polyol is used as a component of a urethane coating composition wherein the polyester polyol comprises a carboxylic acid unit (A) containing at least a part of dimer or more oxy carboxylic acid oligomer unit (a) prepared by condensation of carboxylic acids of castor oil aliphatic acid or the like, and a polyhydric alcohol unit (B). Moreover, Patent Document 5 discloses that a polyurethane foam for automobile seats is prepared by adding at least one molecule of alkylene oxide to a plant fat and oil such as castor oil or its derivative, and allowing a polyol having a hydroxyethyl group at the molecule chain end to react with an isocyanate compound. Patent Document 6 discloses that a soft polyurethane foam prepared from a polyisocyanate compound and a polyol obtainable by adding ethylene oxide/propylene oxide to an epoxidized soybean oil which is ring opened by alcohol is used as a cushioning material for automobile seats. Patent Document 7 discloses that a polyurethane foam is produced by using a polyester polyol having a specific polyol component structure as a composition for preparing a polyurethane foam having proper hardness and impact resilience as a cushioning material and also by determining the NCO index to a specific value, and further discloses that a plant fat and oil such as castor oil aliphatic acid or the like is preferably used as a raw material for a polyester polyol. Patent Document 8 discloses that, as a cushioning material for car seat cushioning or the like, a plat derived polyurethane foam composition is preferably used for preparing a polyurethane foam having good balance between proper hardness, impact resilience and durability. Patent Document 9 discloses that a plant-derived polyurethane foam having excellent low impact properties, which is suitable for impact absorbing materials, sound absorbing materials and vibration damping materials, is obtainable from a polyurethane foam composition.
However, the polyurethane foam described in Patent Document 1 is a hard polyurethane foam, and therefore a soft polyurethane foam having proper characteristics as a vibration damping and sound absorbing material is not obtained. In the process of Patent Document 2, a castor oil type polyol is used as an additive and the addition amount thereof is from 0.1 to 15% by weight based on the polyhydroxy compound. Particularly, in the example, castor oil type polyol is used in a slight amount of 5% based on all polyol components, and the effect merely shows on curing properties and low compression permanent set. Furthermore, in Patent Documents 3 and 4, polyols having a higher molecular weight as compared with the castor oil type polyol used in Patent Document 1 or 2 are used. In Patent Document 3, this polyol is merely used as an internal mold release agent. In Patent Document 4, the coating composition is merely disclosed. Patent Documents 5, 6, 7 and 8 each disclose the polyurethane foam for automobile seats as the use with general expression, and do not disclose sound absorbing properties. In Patent Document 9, the use includes cushioning materials and mattresses having excellent low impact properties, therefore vibration damping and sound absorbing materials formed from polyurethane foams having vibration damping and sound absorbing properties cannot be obtained.
That is to say, vibration damping and sound absorbing materials containing a plant-derived polyol and having excellent vibration damping and sound absorbing properties cannot be obtained by the processes disclosed in these patent documents.    Patent Document 1: Specification in U.S. Pat. No. 2,787,601    Patent Document 2: JP-A-H5-59144    Patent Document 3: JP-A-S61-91216    Patent Document 4: JP-A-H11-166155    Patent Document 5: JP-A-2005-320437    Patent Document 6: JP-A-2005-320431    Patent Document 7: JP-A-2006-2145    Patent Document 8: WO-2007/020904 A1    Patent Document 9: WO-2007/020905 A1